1. Technical Field
The present invention relates to drivers, electronic devices, and the like.
2. Related Art
Display devices (liquid-crystal display devices, for example) are used in a variety of electronic devices, including projectors, information processing apparatuses, mobile information terminals, and the like. Increases in the resolutions of such display devices continue to progress, and as a result, the time a driver drives a single pixel is becoming shorter. For example, phase expansion driving is used as a method for driving an electro-optical panel (a liquid-crystal display panel, for example). According to this driving method, for example, eight source lines are driven at one time, and the process is repeated 160 times to drive 1,280 source lines. In the case where a WXGA (1,280×768 pixels) panel is to be driven, the stated 160 instances of driving (that is, the driving of a single horizontal scanning line) is thus repeated 768 times. Assuming a refresh rate of 60 Hz, a simple calculation shows that the driving time for a single pixel is approximately 135 nanoseconds. In actuality, there are periods where pixels are not driven (blanking intervals and the like, for example), and thus the driving time for a single pixel becomes even shorter, at approximately 70 nanoseconds.
With the shortening of pixel driving times as mentioned above, it is becoming difficult for amplifier circuits to finish writing data voltages within the required time. A method that drives an electro-optical panel through capacitor charge redistribution (called “capacitive driving” hereinafter) can be considered as a driving method for solving such problems. For example, JP-A-2000-341125 and JP-A-2001-156641 disclose techniques that use capacitor charge redistribution in D/A conversion. In a D/A conversion circuit, both driving-side capacitance and load-side capacitance are included in an IC, and charge redistribution occurs between those capacitances. For example, assume such a load-side capacitance of the D/A conversion circuit is replaced with the capacitance of the electro-optical panel external to the IC and the D/A conversion circuit is used as a driver. In this case, charge redistribution occurs between the driver-side capacitance and the electro-optical panel-side capacitance.
However, there is a problem in that a resistance of an input terminal of the electro-optical panel (a resistance for electrostatic protection, for example) interferes with the movement of charges, resulting in a voltage at an output terminal of the driver temporarily rising above (or falling below) a desired data voltage. In the case where this voltage rise (or fall) exceeds (or falls below) a power source voltage, for example, the charge will escape to the power source via an electrostatic protection element of the driver (a diode provided between the output terminal and the power source, for example), and the charge in the charge redistribution will no longer be conserved. When this occurs, the desired data voltage can no longer be obtained. Alternatively, the rise (or fall) in the voltage will exceed the breakdown voltage of a transistor or the like, which may cause the driver to malfunction.